Photographic emulsion



Patented Feb. 3, 1942 PHOTOGRAPHIC EMULSION Burt H. Carroll and CharlesF. H. Allen, Rochester,-N. Y., assignors to Eastman Kodak Com-- pany,Rochester, N. Y., a corporation of New Jersey No Drawing. ApplicationFebruary 29, 1940,;

Serial No. 321,593

. l Claims. This invention. relates to photographic emulsions and moreparticularly to photographic emulsions of the silver halide type.

It is known that the inherent sensitivity of photographic silver halideemulsions (whether spectrally sensitized or not) can be enhanced, andthere has been a constanteiiort to obtain higher speeds in photographicemulsions. For

example, it is-known that the speed of gelatino- -silver-halideemulsions can be enhanced by an extended digestion or ripening of theemulsion. It is also known that the speed of silver halide emulsions(spectrally sensitized or not) can vbe enhanced by incorporating in theemulsions compounds containing a divalent atom of the sulfur groupdirectly joined by a double bond to a single metalloid atom to which isattached at least another group of atoms. Examples of such compounds areallyl isothiocyanate and allylthiourea. s

We have now found that the speed of photographic silver halide emulsionscan be increased by incorporating in the emulsions (spectrallysensitized or not) surface active substances, such as aqueous-dispersingor wetting agents, of the cationic phosphonium salt type. (Surfaceactive substances are classified as anionic or cationic Thesurface-active substances act on the emulsion in unknown manner toincrease its effective sensitivity. As a result, the sensitivity isprovement over supersensitized emulsions known in the art. The increasesin sensitivity which can be attained with-supersensitizingcombinaincreased by about the same amount at any substances and spectral(optical) sensitizers as combinations, although we do not intend toimply that the surface-active substances andv the spectral sensitizerare chemically combined.

Our new. supersensitized emulsions are an imtions of dyes can beenhanced by our new method. Furthermore, whereas with supersensitizingcombinations of sensitizing dyes (see United States Patents 2,075,047,2,075,048 and 2,075,049,

each dated March 30, 1937), the supersensitizing effect is confined moreor less to a single spectral region, the supersensiti'zation attained inour new emulsions extends throughout the entire region in which thespectral sensitizer acts (and is fairly uniform in degree throughout theentire region), while at the same time the sensitivity in the violet andblue region (where the spectral sensitizer does not act) is alsoenhanced about to the same degree.

in a suitable solvent, such as water or methyl alcohol. Thesurface-active substance should be thoroughly incorporated in theemulsion. The

surface active substance 'can be added to the I finished emulsion or atany stage of the preparation of the emulsion.

In the case of spectrally sensitized emulsions,

' the surface-active substance can be incorporated in the emulsionbefore, simultaneously with, or'

after the sensitizing dye, although in some cases as hereinafter setforth, it is advantageous to incorporate the sensitizing dye beforeincorporating the surface-active substance. The methods of incorporatingsensitizing dyes in emulsionsare, of course, well known to those skilledin the art. Ordinarily, it is advantageous to employ a solution of thesensitizing dye in a suitable solvent, e. g. methyl alcohol. Ethylalcohol or acetone may be employed in cases where the ,solubility of thesensitizing dye in methyl alcohol is very low, or any other suitablesolvent or other procedure may be used.

sensitizing dyes are ordinarily incorporated inthe washed, finishedemulsions. and in accordance with our invention, the surface-activesubstances are advantageously also incorporated in q the washed,finished emulsions. However, the

surface-active substances can-be added to the emulsion during thepreparation thereof, 1. e..

during the precipitation of the silver halide, the

' mono salts.

mono salts, the phosphonium cation should advantageously contain atleast seven, eight or more members. Advantageously, such members arefrom the group consisting of carbon, oxygen, nitrogen and sulfur atoms.One or more aromatic rings, such as a benzene ring, for example, cantake the place of on or more of the weight or more atoms. Thus, abenzene ring can take the place of one atom, while a naphthalene ring(two benzene rings fused together) can take the place of two atoms. Theatoms attached to the eight or more atoms in the chain (where valencepermits) can be hydrogen, oxygen, sulfur, carbon or halogen, forexample. Any aromatic ring system in the chain can carry simplesubstituents. We have found that cationic phosphonium saltsurface-active substances having a phosphonium cation containing alipophylic organic group which contains a chain composed of from nine totwelve members selected from the group consisting of carbon atoms,oxygen atoms, sulfur atoms and aromatic ring system are advantageouslyemployed.

In the case of "poly salts described in examples hereinafter and also ina copending application filed of even date in the names of the sameinventors, other proportions and the like may be used. For example, inthe case of agents having a bivalent organic radical having a chain of1-6 members, amounts of 400 mg. may be employed. In the instance ofchains of 7-14 members smaller amounts would be preferred, as will bediscussed hereinafter with respect to the The anion may be anyacidradical, such as chloride, bromide, iodide, p-toluenesulfonate,perchlorate or alkylsulfate for example. Of course, introduction ofhalide anions into photographic silver halide emulsions alters thehalide concentration in the emulsion and compensating Nonyl, CHa-(CI-Iz)a-(nine atom chain).

Decyl, CHa(CHz)o-(ten atom chain).

Lauryl, CHa(CHz)11-(twelve atom chain).

Cetyl, CI-I3(CH:)15(sixteen atom chain).

Heptoxymethyl, CHs (CHz)e-O-CHz-(nine atom chain).

Undecoxymethyl, CHa-(CHz) 1c0--CHz(thirteen atom chain).

Heptylthiomethyl, CH3(CH2) e-SCH2 (nine atom chain).

Carbononoxymethyl cH@(cH, ,-o-c :-cH:-

0 (twelve atom chain). Caproiixyethyl CHa-(CHDc-C-O-CHr-CHz- (nine atomchain). Butoxyethoxyethyl, CHa(CH2) aO-(CH:) a

OCH2-CH2(ten atom chain). Ter-butylphenoxyethoxyethyl (eight atom+phenylgroup chain). Formylphenyloxyethoxyethyl (seven atom+phenyl groupchain). Phenylphenoxyethoxyethyl (six atom-i-two phenyl groups chain).Methylphenoxypropoxypropyl (nine atom+phenyl group chain).3,7-dimethyloctanoxymethyl GHr-CH-CHr-OHr-CIL-CH OH-OH.00Hr- I Q Hi HI(ten atom chain). Citronelloxymethyl CH:=CHCHr-CHz-CHz-CH-CHrCHr-O-CHrH; Hr

(ten atom chain).

(Alcohol radicals in commercial oil of san wood)-O-CHz--(at least tenatom chain).

en atom chain) p-Naphthoxyethoxyethyl (six atom two phenyl group chain).We have found it advantageous to incorporate spectral sensitizers in thephotographic emulsions prior to incorporation of the perchloratesurfaceactive substances. With surface-active substances containinganions other than perchlorate.

. the order of incorporation of the surface-active substance withrespect to the spectral sensitizer appears to be of small moment.

The quantity of surface-active substance which is most advantageouslyemployed varies with the nature of the surface-active substance and withthe nature of the emulsion. Ordinarily, the most advantageousconcentration was found to be between about 20 mg. and about 200 mg. ofthe surface-active substance per gram-mole of silver halide in theemulsion, although greater or smaller concentrations. can be employed.We have found that excesses of the surface-active substance areadvantageously avoided, since excesses'produce fog in the emulsions; Forsurface-active substances containing a lipophylic group containing achain of eight to ten memben, we have found-thatas *much'asabout 400 mg.of surface-active substance per gram-mole of silver halide in theemulsion can ordinarily be employed without encountering excessive fog,

while with surface-active substances-containing. a lipophylic groupcontaining a chain of eleven to twelve or more-members, we have'foundthat not more than about 200 mg. of surface-active substance per.gram-mole of silverhalide shouldordinarily be employed.

The preferred amounts withrespect to they "poly salts (which may or maynot be surface active) have already been described, andindicate to someextent the variation with the nature of the salt. I

The optimum range of'concentration for any particular surface-activesubstance described herein is ordinarily fairly narrow and can best bedetermined byemploying -a-seriesof concentrations of the surface-activesubstances, separately of course, well known to those skilled in theart.

Briefly; the method of determining sensitivity of comprises coating theemulsion onto a glass plate to a suitable thickness and drying thecoated emulsion and then testing the resulting photographic plate in awedge spectrograph and a sensitometer, whereby spectral sensitivity andspeed of the emulsion on the plate is determined.

When employing spectrally sensitized emulsions, the spectral sensitizers(sensitizing dyes) are advantageously employed in about their optimumconcentration, which ordinarily lies between about 3 mg. and mg. ofspectral sensitizer'per liter of emulsion containing about 0.25 grammoleof silver halide, although concentrations above or below the optimumconcentration can be employed. with line-grain emulsions, which in- Ieludes most' of the ordinarily employed silver chloride emulsions, theratio of concentration of sensitizing dye to the. concentration ofsilver halide in the emulsion is advantageously larger than in thecoarser grain emulsions where,

iicial eifect on the" emission." As non-acidic sensitizing dyes, weinclude all the knownneutral and basic. sensitizing dyes: ii thosesensitizing dyes which do notg'ive" colored anions. Some of thesenon-acidic sensitizingjjdyes,--such'as the cyanine dyes, give coloredcations. "Exemplary of the non-acidic sensitizing dyes are thesensitizing cyanlne cl'yes (see, for example, United States I Patents1,846,300, 1,846,301, 1,846,302,-1,846,303

smaller amounts. of sensitizing dyes. usually give optimumsensitization. The optimum concentration, as-above referred to, ofasensitizing dye (i. e. the concentration at which greatest sensitivityoccurs) can be readily determined inamanner well known to those skilledin the. art by measuring the sensitivity of a series of emulsionscontaining different concentrations of the sensitizing dye.

Our invention is directed particularly to the silver halidedeveloping-out emulsions customarily employed in the art, including thegelatinosilver-chloride, the gelatino-silver-bromide and 'thegelatino-silver-bromiodide' developing-out emulsions, for example.However, our invention can be employed with silver halide emulsionswherein the carrier is other than gelatin, for example, a resinous orcellulosic. derivative substance which has substantially no deleteriouseffect on the light-sensitive materials in the emulsions.

As spectral practicing our invention. sensitizing dyes, such asCongored,whicl'1 disperse in water to give a colored anion, i. e. acidicsensitizing dyes, appear to interfere with the surface-active agent,with the result that neither the acid dye nor the surface-activesubstance exert a substantially benee and 1,846,304, each. datedFebruary'23,'1932, United States Patent 1,861,836, dated June 7, 1932,United States Patent-1,939,201, dated December 12, 1933, United StatesPatent.1,942-,854, dated. January 9, 1934, United States Patent1,957,869, dated'May 8, 1934, United States Patent 1,962,124, dated June12, 1934, United States Patent 1,969,446, dated August 7, 1934, UnitedStates Patent 1,973,462, dated September 11, 1934; United StatesPatent-1,990,507, dated February 12, .1935, United States Patent2,094,580,v

dated October 5, 1937, United States Patent 2,112,140, dated March ,22,1938 and French Patent 757,813, published January 5, 1934),.the

sensitizing merocyanine dyes.(see United States Patent 2,078,233, datedApril 27,1937, United State Patent 2,089,729, dated August 10, 1937,

United States Patent 2,153,169, dated April 4, f

1939 and United States Patents 2,177,401; 2,177,402, and 2,177,403,dated October 24, 1939) the sensitizing hemicyanine dyes (see United J 7States Patent 2,166,736, dated Jilly 18, 1939) and the sensitizinghemioxonol dyes, (see United States Patent 2,165,339, dated July 11,'1939 and French Patent 841,632, published May 24, 1939) A furtherunderstanding of our invention will be had from a consideration'of thefollowing ex-' amples. It is to be understood that these ex-' amplesare'set forth primarily for the purposes of illustrating preferredembodiments and not for limiting our invention.

While phosphonium compounds from any source, as long as they areofsatisfactory purity and otherwise meet photographic specifications,

may be employed, we describe herein examples of y the manufacture ofcertain of our compounds. The several examples immediatelyfollowing,.are illustrations of some of the procedures which may befollowed in making various phosphonium derivatives'useful in practicingour invention.

Exams: 1. n-Dodecyltriethylphosph'onium bromide The mixture was heatedunder reflux at 125 C.

' for 2 hours. on cooling the mass solidified and sensitize rs (sensitizlng dyes) only those which are non-acidic can be employed in 3% partsof n-dodecyltriethylphosphonium bro-lmide was collected by .treatingwithanhydrous ether. I

Exurru: 2.n-Dodecyltriethylplgosphonium perchlorate Approximately '2parts of n'-dodecyltriethylphosphonium bromide (from Example 1) was.

treated in 5 parts of methyl alcohol with 2 parts ofsodium perchloratein 5'pa'rts of warm water and chilled. By this treatment there isobtained l-2 parts of 'n-dodecyltrithylphosphonium perchlorate, meltingat 70 (3,

. Exmrts 3.-n -Decyltriethylphosphonidm p-toluenesullonate A mixture of4 mshsema triethylphosphine (obtained by the action of phosphorustribromide at 125-l35 C.under reflux. While still 'warm betterunderstanding of our invention, we, set

forth an example describing the specific addition of one of ourreagents'to a certain photographic emulsion. Likewise, it is to beunderstood that the product was treated with 15 parts of acetone 5 thisexample is set forth merely for the purpose which efiected solution.There was then added of illustration 'and is not to be considered'a re-30 parts of ether, and on. chilling 4 parts of a striction on ourinvention.

white salt melting at 61-65 C. crystallized. It Emil: 6

was essentially n-decyltriethylphosphonium ptoluenesulfonate, 10 Ahighly sensitive silver bromiodide gelatin was optically sensitized togive a panchromatic sensigf m fsf'gfx tization and divided into twoportions. One of e i v the portions was employed as a control. To the To6 partsof crude triethylphosphine (obother portion was addedapproximately 10 mg. tained by the action of phosphorus tribromide perliter. of n-lauryltriethylphosphonium broon ethylmagnesium bromide) wasadded 6 parts mide, in accordance with our invention; Several ofdecamethylene bromide and the mixture plates were coated from eachportion aforedewarmed slightly. A vigorous reaction set in and scribed,dried together, exposed together, and

a white solid separated. After cooling, the repro ss d together. inorder t t all nd ns action product was dissolved in parts of meth- 20would be comparable and the beneficial efiects yl alcohol and allowed tostand until the bulk of our novel addition f. ph p ni compounds of thealcohol had evaporated. It was then r y p r treated with 20 parts ofether, and the white p n t s n h p ss p a s. t u ms crystalline materialresulting was collected on a Sensitivitles noted were as 1 filter, Therewas thus obtained 10 parts of tetramethylene-bis-triethylphosphoniumbrom- Speed 1 r ide melting at 158 C.

Exem t: 5. hillene-bis-ory e hyltriethylfififititsiimaattainments;165.517

. phosphoiiium chloride 1,860 pazts :2 i ether l of triezhyl Variousother phosphonium compounds could f g con a g an l g' of be incorporatedin a similar manner, as for exg 3 8 .f e amplen-lauryltriethylphosphonium perchlorate, oxyme y c or e and 6 mm umwarme to n-decyltriethylphosphonium p-toluen'esulfonate remove etherandthen heated under reflux for or tetramethylene bis phosphoniumperchloram 3 hours at 120 By treating the product with In all instances,our novel treatment of photoacetone and ether there .was obtained. asmall graphic materials with phosphonium compounds amount of white solidmelting with f not only improved the speed of sensitized emultion at 160C. It was essentially ethylene-bissions but even sensitized emulglonaThe oxymethyl-triethylphosphonium chloride. 7 40 movement as indicatedin the cifi atio with Particular reference to Example 2, further tendedover the entire region, even into the violet details respecting theproduction of perchlorate a blue region and enhanced t en itivityderivatives are Set forth in Allen and Wilson about the same over theentire region. Furtherapplication entitled Surface-active materials,more, t 111 be t d that the improvement may filed of even date. 40.amount to 25% or more.

As already Pointed t. the phosphonillm com- Still further illustrationsof our invention are p d mixture pounds to be added to set forth forconvenience in the following table.

the photographic material may be added in var- It will be. observed fromthe disclosure in the ious ways, various amounts, in the presence oftable that both sensitized and unsensitized photodye sensitizers, orotherwise. However, for a graphic emulsions were treated.

(White light White light minus blue) Emulsion sensitizing dye Surfaceactive agent 12 Speed Gamma Fog Speed Gamma Highly sensitivegelatlno-sil- 2-diphenylamino-fi-(z-ethyl-l- None 455 0.82 .06 126 0.8

ver-bromiodide. benzothiazylidene ethylidene)-4-(6)-thiazolone, 15mg./iiter. Do do Tetramethylene his triethyl 590 0.88 .06 200 0.81 vphosphonium *bromide 30 rug/liter. Do l,2-diethyl-3,4-benzothia-2- None280 0.82 .08 as 0.77

fiytglnine iodide, 15 mg./ Do "do Tetrlmethylene bis triethyl I 72s 0.00.07 0.78

pho7lphonium bromide, 30 mg. iter.

Do 2,7-dimethyl-8-ethyl thiacar- None 525 0.61 .07 132 0.62

lliizg yanine bromide, 15 mg./ Db .do 'letmmethylene bis trietbyl 0150.70 .0a 178 0.79

' Mama Ilium bromide Do Unsensitiwd emulsion are iii 000 0.01 .04 Do..do Totramotliyienc bis trietiiyl 830 0.60 .06

' g alumni bromide 30 Therefore, it will be seen that we have found'that a substantial improvement may be made in photographic emulsions byincorporating a phosphonium compound or compounds therein in variousways. As indicated,- in the instance where the photographic materialcontains a sensitizing dye, it is preferred to incorporate the dyesensitizer first and thereafter incorporate the phosphoniumsurface-active substance.

In the production of our various compounds, in place of theethersolvent, other suitable solvent may be employed. Or, other changesmay be made in the process.

It is apparent from the foregoing'that our in vention is susceptible ofsome modification and hence is not to be restricted excepting insofar asmay be necessitated by the prior art and the spirit of the appendedclaims.

.What we claim as our invention and desire to be secured by LettersPatent of the United States 1. A photographic. silver halide emulsionsensitized with a cationic surface-active phosphonium salt.

2. A photographic silver halide developing-out emulsion sensitized witha cationic surface-active phosphonium salt.

3. A photographic gelatino-siiver halide emulsion sensitized with a.cationic surface-active phosphonium salt.

4. A photographic gelatino-silver-halide developingrout emulsionsensitized with a cationic surface-active phosphonium salt.

5. A photographic gelatino-silver-halide emulsion sensitized with asupersensitizing combina tion of at least one non-acidic sensitizing dyetogether with a cationic surface-active phosphonium salt.

6. A photographic silver halide emulsion sensitized with a cationicsurface-active quaternary phosphonium salt.

7. A photographic silver halide developing-out emulsion sensitized witha cationic surface-active quaternary phosphonium salt.

8. A photographic gelatino-silver-halide emulsion sensitized with acationic surface-active quaternary phosphonium salt.

9. A photographic gelatino-silver-halide developing-out emulsionsensitized with a cationic surface-active quaternary phosphonium salt.

10. "A photographic silver halide emulsion sensitized with asupersensitizing combination of at least one non-acidic sensitizing dyetogether with a cationic surface-active quaternary phosphonium salt.

11. A photographic gelatino-silver-halide emulsion sensitized with asuper-sensitizing combination of at ,least one non-acidic sensitizingdye together with a cationic surface-active quaternary phosphonium salt.

12. A photographic emulsion sensitized with a supersensitizingcombination of a non-acidic sensitizing dye together with a cationicsurface active quaternary phosphonium salt, thejcation of which containsat least one organic group containing a chain of at least eight membersselected from the group consisting of carbon atoms, oxygen atoms, sulfuratoms, nitrogen atoms and benzene nuclei.

13. A photographic gelatino silver -halide emulsion sensitized with asupersensitizing combination of a non-acidic sensitizing dye togetherwith a cationic surface active quaternary phosphonium salt, the cationof which contains at least one organic group containing a chain of fromeight to twelve members selected from the .group consisting of carbonatoms, sulfur atoms,

oxygen atoms, nitrogen atoms and benzene nuclei.

14. A photographic gelatino silver halide emulsion sensitized with atleast one non-acidic sensitizing dye and containing, in a concentrationof from about 20 ,to about 400 milligrams per gram-mole of silver halidein the emulsion, a cationic surface active quaternary phosphonium salt,the cation of which contains at least one organic group containing achain of from 8 to 10 members'selected from the group consisting ofcarbon atoms, sulfur atoms, oxygen atoms, nitrogen atoms and benzenenuclei.

15. A photographic gelatino silver halide emulsion sensitized with atleast one non-acidicgelatino-silver-halide

